Hammel Elzbieta, Mantziaris Charalampos, Schmitz Joscha, Büschges Ansgar, Gruhn Matthias
Animal Physiology, Biocenter, Mathematisch-Naturwissenschaftliche Fakultät, Universität zu Köln, Cologne, Germany.
Front Physiol. 2022 May 4;13:883858. doi: 10.3389/fphys.2022.883858. eCollection 2022.
We have just started to understand the mechanisms underlying flexibility of motor programs among segmental neural networks that control each individual leg during walking in vertebrates and invertebrates. Here, we investigated the mechanisms underlying curve walking in the stick insect during optomotor-induced turning. We wanted to know, whether the previously reported body-side specific changes in a two-front leg turning animal are also observed in the other thoracic leg segments. The motor activity of the three major leg joints showed three types of responses: 1) a context-dependent increase or decrease in motor neuron (MN) activity of the antagonistic MN pools of the thorax-coxa (ThC)-joint during inside and outside turns; 2) an activation of 1 MN pool with simultaneous cessation of the other, independent of the turning direction in the coxa-trochanteral (CTr)-joint; 3) a modification in the activity of both FTi-joint MN pools which depended on the turning direction in one, but not in the other thorax segment. By pharmacological activation of the meso- or metathoracic central pattern generating networks (CPG), we show that turning-related modifications in motor output involve changes to local CPG activity. The rhythmic activity in the MN pools of the ThC and CTr-joints was modified similarly to what was observed under control conditions in saline. Our results indicate that changes in meso- and metathoracic motor activity during curve walking are leg-joint- and thorax-segment-specific, can depend on the turning direction, and are mediated through changes in local CPG activity.
我们刚刚开始理解在脊椎动物和无脊椎动物行走过程中控制每条腿的节段神经网络之间运动程序灵活性的潜在机制。在此，我们研究了在视动诱导转向过程中竹节虫曲线行走的潜在机制。我们想知道，在先前报道的两前腿转向动物中观察到的身体侧特异性变化是否也会在其他胸腿节段中出现。三个主要腿关节的运动活动表现出三种类型的反应：1）在内转和外转过程中，胸-基节（ThC）关节拮抗运动神经元（MN）池的MN活动根据上下文增加或减少；2）在基节-转节（CTr）关节中，一个MN池激活，同时另一个MN池停止活动，与转向方向无关；3）两个股节-胫节（FTi）关节MN池的活动变化，其中一个胸节段的活动变化取决于转向方向，而另一个胸节段则不然。通过对中胸或后胸中央模式发生器网络（CPG）进行药理学激活，我们表明运动输出中与转向相关的变化涉及局部CPG活动的改变。ThC和CTr关节MN池中的节律性活动变化与在生理盐水中对照条件下观察到的情况相似。我们的结果表明，曲线行走过程中中胸和后胸运动活动的变化是腿关节和胸节段特异性的，可能取决于转向方向，并通过局部CPG活动的变化介导。
